Deflection factor indicating apparatus

ABSTRACT

A switch apparatus is described including a rotary switch operated by a knob having a movable dial flange with display characters thereon at switch positions corresponding to different multiplying factors provided for the output signal of an electrical circuit controlled by such switch. A pair of fixed light sources mounted at two different readout positions beneath the flange are selectively energized by an external multiplier switch to illuminate only one of the factors at such readout positions in accordance with the operation of such multiplier switch. The rotary switch and multiplier switch may be connected to change the gain of a vertical amplifier or to change the sweep speed of a horizontal ramp generator in a cathode ray oscilloscope so that the illuminated character display on the knob dial automatically indicates the proper deflection factors of such oscilloscope.

United States Patent 1 [111 3,725,724 Vollum 51 Apr. 3, 1973 1DEFLECTION FACTOR INDICATING Primary Examiner-Carl D. QuarforthAPPARATUS Assistant Examiner-J. M. Potenza [75] Inventor: Charles HowardVollum, Portland, Attomey BuckhmBloremarqulstg Sparkman Ore g [57]ABSTRACT [73] Assignee: Tektronix,lnc.,Beaverton,Oreg.

A switch apparatus lS described mcludmg a rotary Flledi J 1971 switchoperated by a knob having a movable dial [21] APP] No; 105,336 flangewith display characters thereon at switch positrons corresponding todifferent multiplying factors provided for the output signal of anelectrical circuit [52] US. Cl. ..3l5l24, 200/167 A, l78/ 7.5 Scontrolled by such switch. A pair of fixed light sources CL "H011mounted at two different readout positions beneath [58] heldSea'ch"315/24;20O/167 A; 173/75 SE the flange are selectively energizedby an external multiplier switch to illuminate only one of the factors[56] References at such readout positions in accordance with the UNITEDSTATES PATENTS operation of such multiplier switch. The rotary switchand multiplier switch may be connected to change the 2,665,343 1/1954Benson ..200/l67A gain of a vertical amplifier or to change the Sweep2,711,711 6/1955 Harman v A speed of a horizontal ramp generator in acathode ray 3 325;? 10/1969 "315/24 oscilloscope so that the illuminatedcharacter display l 4/1961 Dunn et al on the knob automaticallyindicates the p p deflection factors of such oscilloscope.

14 Claims, 3 Drawing Figures MULTIPLIER CONTROL 4O 38 W X SWITCH VERT.AMP

HOR. SWEEP PATENTEUAPR3 I975 3,725,724

MULTlPLIER J CONTROL 4O 38 l 20 W XIO VERT. AMP, I4 32 OR 7 l l HOR.SWEEP 222 24 VIA\\I 1 A 28 f 2 5 1D [6 si N CHARLES HOWARD VOLLUMINVENTOR BUCKHORN, BlORE, KLARQUIST & SPARKMAN ATTORNIYS DEFLECTIONFACTOR INDICATING APPARATUS BACKGROUND OF THE INVENTION The subjectmatter of the present invention relates generally to switch apparatusand associated indicating means, and in particular, to such a switchapparatus including a movable dial with two selectively illuminatedreadout positions. A deflection factor indicating apparatus is disclosedincluding a rotary switch with a knob having a dial flange with displaycharacters thereon at its switch positions for indicating differentsignal multiplying factors provided by such rotary switch alone or incombination with a multiplier switch by selectively energizing a pair oflight sources at two different readout positions in response tooperation of the multiplier switch to illuminate only one factor displayat the proper readout position corresponding tothe condition of suchmultiplier switch.

The present invention is especially useful on cathode ray oscilloscopesfor indicating the deflection factor of such Oscilloscopes by employingit in connection with the rotary switch controlling either the amplitudegain of the vertical amplifier or the sweep time of the horizontal rampsweep generator when such deflection factors are changed by an externalfactor multiplier switch or other means external to the rotary switch.Thus, the gain of the output signal of the vertical amplifier can bereduced a predetermined amount by connecting an attenuator probe to theinput of such amplifier as one example of an external multiplying means.Another example would be a sweep magnifier" switch connected to thehorizontal sweep generator for increasing the sweep time of its outputsignal by reducing the slope of its ramp shaped waveform by a knownfactor.

Previously, it was necessary for the operator of the oscilloscope toperform mental calculations including multiplying the externalmultiplier factor times the reading of the rotary knob on the frontpanel of the oscilloscope to determine the proper deflection factor ofthe signal displayed on such oscilloscope. As a result, many operatorerrors occurred in reading the vertical amplitude and horizontal timevalues of the signal displayed due to failure to multiply the knobreadings by the proper external multiplying factor. This problem isavoided in the present invention because the proper deflection factor isautomatically illuminated on the rotary knob at all times.

Conventional switches employ a movable pointer on the switch knob andthe switch position indicating numbers are fixed on thefront panel ofthe oscilloscope or other instrument. The present invention reversesthis and, instead, uses movable indicating numbers on the knob andprovides a fixed pointer in the form of a light source positioned behinda masking aperture in the front panel of the oscilloscope. This reducesthe mounting space required on the front panel of the oscilloscope. Inaddition, by providing an illuminated readout rather than merely using apointer, the switch factor indicating apparatus of the present inventioncan be read more easily and is visible in a darkened room. These are twoadditional advantages over the prior art.

It is, therefore, one object of the present invention to provide animproved switch apparatus having a deflection factor indicating means ofsimple and economical construction which automatically indicates theproper factor when an external multiplier means has been operated inaddition to the main switch with which the indicator means isassociated.

Another object of the invention is to provide such a switch apparatus inwhich the indicator numbers are provided on a movable dial memberrotated by the knob of such main switch past a pair of fixed lightsources at two readout positions which are selectively energized inaccordance with the operation of the external multiplier means toprovide an illuminated character display of the proper factor.

A further object of the invention is to provide such switch apparatus inwhich the main switch and external multiplier means areconnected to thevertical amplifier or the horizontal sweep generator of a cathode rayoscilloscope to change the amplitude gain of the vertical output signalor to change the sweep time of the horizontal sweep signal and toautomatically indicate the proper deflection factor of the signaldisplayed on such oscilloscope.

Still another object of the invention is to provide a switch apparatushaving a movable dial on the switch knob and a fixed pointer lightsource beneath such dial which occupies less mounting space and isvisible under dim ambient lighting conditions.

BRIEF DESCRIPTION OF DRAWINGS Other objects and advantages of thepresent invention will be apparent from the following detaileddescription of a preferred embodiment thereof and from the attacheddrawings of which:

FIG. 1 is a plan view with parts broken away for purposes of clarity ofone embodiment of the deflection factor indicating apparatus of thepresent invention together with a schematic diagram of electricalcircuitry associated therewith;

FIG. 2 is a front elevation view of the knob employed in anotherembodiment of the deflection factor indicating apparatus of FIG. 1;

FIG. 3 is a vertical section view taken along the line 3-3 in FIG. 2.

DESCRIPTION OF PREFERRED EMBODIMENT As shown in FIG. 1, one embodimentof the deflection factor indicating apparatus of the present inventionincludes a knob 10 mounted on a rotatable shaft 12 which is coupled to arotary switch 14 connected to an electrical circuit for changing theamplitude or time characteristics of its output signal as hereafterdescribed. The knob has an outer flange or skirt 16 extending radiallyoutward and forming a movable dial on which are provided a plurality ofindicator characters 18. The indicator characters may be in the form ofnumbers corresponding to multiplying factors which are set by thedifferent switch positions of the rotary switch 14 and of an externalmultiplier switch 20 separated from and external to such rotary switch.

The external multiplier switch 20 may have two positions, including atimes one position (X1) and a times ten position (X10) in which thestationary contacts of such switch positions are connected respectivelyto a pair of fixed light sources 22 and 24 which act as pointers for thedial 16. The movable contact of the external multiplier switch 20 isconnected to a source of positive DC voltage to selectively energizelight source 22 or light source 24 depending on the position of suchswitch. A light opaque mask member 26 which may be the front panel of acathode ray oscilloscope is provided with a pair of masking apertures 28and 30 in alignment with light sources 22 and 24, respectively, to formtwo different readout positions for the dial 16. Thus, the light sourcesselectively illuminate the indicator numbers 18 to provide a characterdisplay of only one of the factors at such readout positions withoutdisplaying the other factors on the dial 16.

In the embodiment shown in FIG. 1, the display characters 18 forming thefactors are provided as light transparent openings extending through alight opaque plastic flange 16. Light rays 31 emitted by light sources22 or 24 are transmitted through the selected characters 18 in thereadout positions to illuminate the characters. In the shown positionsof the knob and the external multiplier switch 20, the factor l will beilluminated on the dial 16 by light source 22 since only such lightsource is energized corresponding to a condition when there is noexternal factor multiplier. However, in the other condition, whenmultiplier switch is moved to the X 10" position, light source 24 isenergized and the other light source 22 is de-energized so that thefactor 10 is illuminated on the dial. Thus, the correct multiplyingfactor is automatically indicated by illuminating the proper factor 18on the dial 16.

The light sources 22 and 24 each may be of the gas lamp type, includinga sealed glass envelope containing a light emitting gas, such as neon,and two spaced electrodes, one of which is grounded and the other isconnected to the switch 20 to provide a long lifetime light source.However, it may be desirable to employ an incandescent filament typelightbulb to provide a brighter light source of shorter lifetime.

The rotary switch 14 has a pair of output conductors 32 which areconnected to an electrical circuit 34, such as the vertical amplifier orhorizontal sweep generator of a cathode ray oscilloscope including acathode ray tube 36 whose deflection plates are connected to the outputsof such vertical amplifier and such sweep generator. In the case of avertical amplifier, the rotary switch 14 changes the gain of suchamplifier to adjust the voltage amplitude of the vertical output signalof such amplifier circuit by predetermined amounts or factors indicatedby illuminated character display 18 on the dial 18. In the case of ahorizontal sweep generator, the rotary switch 14 changes the sweep speedto adjust the slope of the leading edge of the ramp shaped voltageforming the horizontal sweep signal produced at the output of such sweepgenerator by predetermined amounts or factors indicated by anilluminated character display 18 on the dial 16.

The external multiplier switch 20 is shown connected through a conductor38 between the X10 contact of such switch and a control terminal of theelectrical circuit 34. This changes the gain of the vertical amplifieror the sweep speed of the horizontal sweep generator by a factor of 10.It should be noted that a coupling capacitor 40 may be provided in lead38 to prevent the DC supply voltage of the electrical circuit 34 frombeing transmitted to the light source 24 to energize such light source.Of course, it may be desirable instead to provide the X10 control signalto the circuit 34 from another switch which is ganged to the externalmultiplier switch 20, but this has not been shown for purposes ofsimplicity.

The external multiplier switch 20 is operated by a multiplier controlmeans 42 which may be a push button or sliding knob provided on anelectrical probe connected to the input of the vertical amplifier or asthe sweep magnifier switch on the front panel of a sweep generatorplug-in unit. Alternatively, the multiplier control means 42 may beprovided on a coaxial cable connector attached to the input of thevertical amplifier and adapted to be engaged by another connector on theoutput end of the probe cable for automatically switching the multiplierswitch 20 to the X10 position when such cable is connected. Also, itshould be noted that an electronic switch can be employed in place ofthe mechanical switch shown for the external multiplier switch 20.

As shown in FIGS. 2 and 3, the rotary switch knob of FIG. 1 can bemodified to provide a knob 10 having a light transparent outer flange 16which is provided with factor display characters 18 formed astransparent image portions of a film negative layer 44 coated on theback side of the knob. Thus, the display characters 18' are provided aslight transparent portions of the layer 44 and the remaining portions ofsuch layers are light opaque. In this embodiment, like that of FIG. 1,the light rays 31 emitted from the light sources 22 and 24 still passthrough openings 28 and 30 in the mask 26 to illuminate only one of thefactor character displays 18 at each of the two readout positions inalignment with such apertures.

It will be obvious to those having ordinary skill in the art that manychanges may be made in the details of the above-described preferredembodiment of the present invention without departing from the spirit ofthe invention. For example, the factor indicating means provided on theflange 16 may be a separate member coupled to the knob 10 for rotationtherewith or light opaque characters can be employed on a lighttransparent dial flange 16. Therefore, the scope of the presentinvention should only be determined by the following claims.

I claim: 1. Deflection factor indicating apparatus comprising: switchmeans including a knob for changing the connections in an electricalcircuit to provide different multiplying factors which vary theamplitude or time characteristics of the output signal of said circuit,by movement of the knob between different switch positions correspondingto said factors;

indicator means moved by said knob and having display characters thereonfor indicating said factors at said switch positions of said knob;

illumination means including two light sources located at two differentreadout positions adjacent said indicator means for illuminating onlythe display characters of one factor at each of said readout positions;and

control means for selectively energizing said two light sources inaccordance with the operation of an external factor multiplier meansseparate from said switch means, for changing the selected factor fromthat set by said switch means independent of movement of said knob.

2. Apparatus in accordance with claim 1 in which the switch means is arotary switch and the indicator means is a dial flange extendingradially outward from said knob which rotates with said knob.

3. Apparatus in accordance with claim 2 in which the display charactersare provided in light transparent areas on said flange.

4. Apparatus in accordance with claim 1 in which the display charactersare light transparent and said light sources project light through theselected characters in said readout positions.

5. Apparatus in accordance with claim 4 in which the illumination meansincludes a light opaque mask member mounted between said characters andsaid light sources, said mask member having a pair of aperturestherethrough in alignment with only the characters at said two readoutpositions.

6. Apparatus in accordance with claim 1 in which the electrical circuitis the vertical amplifier of a cathode ray oscilloscope and the factoris the vertical deflector amplitude factor.

7. Apparatus in accordance with claim 6 in which the external multipliermeans is an electrical probe means connected to the input of thevertical amplifier for changing the gain of the output signal of saidamplifier.

8. Apparatus in accordance with claim 1 in which the electrical circuitin the horizontal ramp generator of a cathode ray oscilloscope and thefactor is the horizontal deflection time factor.

9. Apparatus in accordance with claim 8 in which the external multipliermeans is a sweep magnifier switch means connected to the ramp generatorfor changing the slope of the leading edge of the ramp output signal ofsaid generator.

10. Apparatus in accordance with claim 1 in which the light sources area pair of light bulbs each connected to an external multiplier switchmeans for selectively energizing said light bulbs one at a time indifferent positions of said external switch means.

1 1. switch apparatus comprising: switch means including knob means forchanging the setting of said switch means by movement of said knob meansbetween a plurality of different switch positions; indicator means movedby said knob means and having display characters thereon for indicatingthe settings of said switch means at said switch positions of said knobmeans; and illumination means including spaced light source meansmounted adjacent said indicator means with one of said light sourcemeans illuminating one of said display characters at a selected switchposition while the other of said light source means is non-illuminatedand the other of said light source means illuminating another of saiddisplay characters at the selected switch position by control meansseparate from said switch means while the said one of said light sourcemeans is non-illuminated independent of movement of said knob means. 12.Apparatus in accordance with claim 11 in which the switch means is arotary switch and the indicator means is a dial flange extendingradially outward from said knob means which rotates the knob.

13. Apparatus in accordance with claim 12 m Wl'llCh the displaycharacters are light transparent and the light source means projectslight through the selected characters.

14. Apparatus in accordance with claim 12 in which the illuminationmeans includes a light opaque mask member mounted between said lightsource means and said flange with an aperture therethrough in alignmentwith said light source means and said selected characters.

1. Deflection factor indicating apparatus comprising: switch meansincluding a knob for changing the connections in an electrical circuitto provide different multiplying factors which vary the amplitude ortime characteristics of the output signal of said circuit, by movementof the knob between different switch positions corresponding to saidfactors; indicator means moved by said knob and having displaycharacters thereon for indicating said factors at said switch positionsof said knob; illumination means including two light sources located attwo different readout positions adjacent said indicator means forilluminating only the display characters of one factor at each of saidreadout positions; and control means for selectively energizing said twolight sources in accordance with the operation of an external factormultiplier means separate from said switch means, for changing theselected factor from that set by said switch means independent ofmovement of said knob.
 2. Apparatus in accordance with claim 1 in whichthe switch means is a rotary switch and the indicator means is a dialflange extending radially outward from said knob which rotates with saidknob.
 3. Apparatus in accordance with claim 2 in which the displaycharacters are provided in light transparent areas on said flange. 4.Apparatus in accordance with claim 1 in which the display characters arelight transparent and said light sources project light through theselected characters in said readout positions.
 5. Apparatus inaccordance with claim 4 in which the illumination means includes a lightopaque mask member mounted between said characters and said lightsources, said mask member having a pair of apertures therethrough inalignment with only the characters at said two readout positions. 6.Apparatus in accordance with claim 1 in which the electrical circuit isthe vertical amplifier of a cathode ray oscilloscope and the factor isthe vertical deflector amplitude factor.
 7. Apparatus in accordance withclaim 6 in which the external multiplier means is an electrical probemeans connected to the input of the vertical amplifier for changing thegain of the output signal of said amplifier.
 8. Apparatus in accordancewith claim 1 in which the electrical circuit in the horizontal rampgenerator of a cathode ray oscilloscope and the factor is the horizontaldeflection time factor.
 9. Apparatus in accordance with claim 8 in whichthe external multiplier means is a sweep magnifier switch meansconnected to the ramp generator for changing the slope of the leadingedge of the ramp output signal of said generator.
 10. Apparatus inaccordance with claim 1 in which the light sources are a pair of lightbulbs each connected to an external multiplier switch means forselectively energizing said light bulbs one at a time in differentpositions of said external switch means.
 11. switch apparatuscomprising: switch means including knob means for changing the settingof said switch means by movement of said knob means between a pluralityof different switch positions; indicator means moved by said knob meansand having display characters thereon for indicating the settings ofsaid switch means at said switch positions of said knob means; andillumination means including spaced light source means mounted adjacentsaid indicator means with one of said light source means illuminatingone of said display characters at a selected switch position while theother of said light source means is non-illuminated and the other ofsaid light source means illuminating another of said display charactersat the selected switch position by control means separate from saidswitch means while the said one of said light source means isnon-illuminated independent of movement of said knob means. 12.Apparatus in accordance with claim 11 in which the switch means is arotary switch and the indicator means is a dial flange extendingradially outward from said knob means which rotates the knob. 13.Apparatus in accordance with claim 12 in which the display charactersare light transparent and the light source means projects light throughthe selected characters.
 14. Apparatus in accordance with claim 12 inwhich the illumination means includes a light opaque mask member mountedbetween said light source means and said flange with an aperturetherethrough in alignment with said light source means and said selectedcharacters.